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connection with these plants is the fact that when they 
have yielded their crop they have not exhausted the soil 
‘of its nitrogen compounds, but will be found to have 
actually enriched it. This renders leguminous plants a 
valuable crop to alternate with other crops which deplete 
the soil of nitrogenous material. In agriculture it is often 
found expedient in the case of poor or exhausted fields to 
dig in a leguminous crop such as lupins or clover, which 
are often grown for the purpose of enriching the soil. 
With a view to increasing the number of the nitrify- 
ing organisms in the soil attempts have been made in this 
and other countries to introduce more of these bacteria, 
particularly into pots or beds in which sweet peas or other 
members of that family are to be grown. In England 
preparations of these bacteria were distributed some years 
ago as “nitrobacterine,” but the use of this preparation 
was not found profitable in all cases, probably as in many 
soils there is already a sufficient supply of these bacteria. 
Professor Bottomley has, however, now discovered a better 
way of cultivating these bacteria in peat, with which they 
can be easily distributed. Peat, which represents the 
partially decayed vegetable remains, differs from leaf 
mould or humus in undergoing decay under very wet con- 
ditions. | As a consequence it remains permeated with 
certain substances which render it acid and unsuited to the 
growth of most plants, though heaths, azaleas, rhododen- 
drons, and other members of the heather family grow 
well in peaty soil. When rendered alcaline, however, peat 
has been found to favour the dévelopment of roots, and 
therefore the whole growth of plants, and containing as it 
does a large amount of organic material, much of which 
is rendered soluble when alcaline, it has a high manurial 
value. This is said to be still further increased by inocu- 
lating the peat with nitrifying bacteria, which grow very 
vigorously in alcaline peat and thus increase the available 
plant foods. “ Bacterised peat,” as it is called, is not yet 
-on the market, and has therefore not been extensively 
tried, but experiments which have been conducted at Kew 
Gardens with pot plants, and on a farm near Norwich, are 
of considerable promise.* 
_* The Spirit of the Soil.” An account of the nitrogen fixation 
in the soil by bacteria, and of the production of auximones as 
promoted by bacterised peat. By G. D. Knox. Constable, 
London, 1915. 
